1.

What is the expression for system function in z-domain?(a) \(\frac{2}{T}[\frac{1+z^{-1}}{1-z^1}]\)(b) \(\frac{2}{T}[\frac{1+z^{-1}}{1-z^1}]\)(c) \(\frac{T}{2}[\frac{1+z^{-1}}{1-z^1}]\)(d) \(\frac{T}{2}[\frac{1-z^{-1}}{1+z^{-1}}]\)I got this question in a job interview.My enquiry is from Bilinear Transformations topic in division Digital Filters Design of Digital Signal Processing

Answer»

The CORRECT answer is (c) \(\frac{T}{2}[\frac{1+z^{-1}}{1-z^1}]\)

Explanation: We know that

y(n)-y(n-1)= \([\frac{x(n)+x(n-1)}{2}]T\)

Taking z-transform of the above EQUATION gives

=>Y(z)[1-z^-1]=([1+z^-1]/2).TX(z)

=>H(z)=Y(z)/X(z)=\(\frac{T}{2}[\frac{1+z^{-1}}{1-z^1}]\).



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